Almost all aircraft are equipped with exterior lights. In particular, large passenger air planes are provided with a wide variety of exterior lights. Examples of such lights include navigation or position lights, beacon lights, anti-collision lights or strobe lights, wing lights, taxi lights, landing lights, runway turnoff lights, etc. All of these lights are respectively provided with at least one light source.
In the past exterior aircraft lights had been equipped with high power incandescent lamps operating at high temperatures. Today's exterior aircraft lights often employ LED light sources. LED light sources do not nearly get as hot as incandescent lamps and therefore are not as efficient in evaporating water and moisture from inside the housing of the aircraft light as incandescent lamps.
Thus, using exterior aircraft lights in humid ambient conditions may lead to humid air ingressing into the housing and eventually to water condensing on a cover lens, in particular when the light cools off after operation. For lights having body mounted LEDs, such a situation is especially prominent as the back-side is thermally insulated and the lens cools off faster than any other part of the housing. Condensed water is considered an issue, as the water droplets modify the light distribution and minimum intensity requirements on the illuminated area might no longer be achieved.
It therefore would be beneficial to provide an exterior aircraft light unit which allows for reducing the risk of condensation within its housing.